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Uncovering the Late Jurassic In Wyoming

The Morrison Formation is one of the most famous dinosaur fossil sites in North America. Early expeditions in the 19th century focused on the fossil remains of large animals, but today Curator of Paleontology Mark Norell and his team are searching for fossils of species that were previously overlooked.

May 201905:59 min

[AMNH logo unfolds over overhead footage of a paleontological dig.]

MARK NORELL(Macauley Curator, Division of Paleontology):When people go out say they want to look for dinosaurs, everybody always ask this, where do you want to dig? So this year we’re excavating in the south end of the Big Horn Basin, in the Morrison Formation, looking at dinosaurs.

The Morrison Formation is one of the most iconic formations within paleontology, because it’s the place where the first great dinosaur discoveries were made in North America. It has brontosaurus, it has stegosaurus, it has the dinosaur species that everybody on the planet has heard of.

This expedition is the 2018 installment of the American Museum Niarchos project. So, this is a joint project that’s run between the American Museum and the University of Lisbon, and my colleague, Octávio Mateus.

OCTÁVIO MATEUS (New University of Lisbon, Portugal): We have to imagine 150 million years ago this as a big plain with some vegetation, a few forests, very large rivers, and the entire ecosystem preserved. And it gives a good glimpse, a good photograph of the life during the late Jurassic.

One of the goals of having this expedition is also having a training ground for our students in paleontology. We run the Masters in Paleontology in Portugal and we invite the students to come here to dig.

Let’s keep this one protected with film.

NORELL: The basic way that we extract fossils from the ground is just like, you know, Barnum Brown did when he was tearing around here and stuff in the 1890s.

MATEUS: We are still using the same techniques that Barnum Brown and others have done. So, we still use the hammer and chisel and brushes. It’s always a destructive process.

NORELL: A typical day in the field is all weather-dependent, but you get up, go out there, and you just sit there and pound rocks all day.

[LAUGHS]

NORELL: We can’t use dynamite anymore, which I wish we could.

[LAUGHS]

NORELL: Hey, Octávio, I think this might be a bone. Like a surface. This rounded thing here.

MATEUS: Yeah, looks like it.

NORELL: So, if it is, this could be like a therapod metatarsal.

If you make an assessment to excavate, then you just start digging. And you start pretty far away and you go closer and closer and closer and closer, until it feels safe. Then you do the jacketing process, which is just like covering it with toilet paper and burlap infused with plaster of Paris and then let that dry. Crack it on the bottom. Have that dangerous moment of flipping it over when you hope that the whole thing isn’t going to fall on the top of it, which has happened. And then plaster the bottom of it.

The Morrison Formation isn’t just dinosaurs. There’s a tremendous number of other fossils which have been found there. When the early dinosaurs came out during the big dinosaur rush in the late 19th century, they dismissed a lot of the smaller animals, because they were looking for big animals to fill their dinosaur halls.

And that’s one of the reasons that we started this excavation, is to try to fill in the picture, by looking at the stuff that was ignored by all the earlier collections. It gives us one of the best pictures of the origin of a lot of the major animal groups—be they frogs, be they lungfish, be they….

MATEUS: …a turtle, perhaps. A pterosaur. So, all those animals which are more obscure, harder to find, hard to preserve and that will tell us a lot about the environment around here.

NORELL: Well, this year we have two sites that are about 5 kilometers apart. But they’re quite different, in some senses. In one place, the material that we excavated is very sandy and soft. The other place is more what we call “indurated,” meaning that it’s harder and we have to use more jackhammers and that kind of thing.

We’re still early in this whole project here, because we’ve been at it for three years now. But we’re just going to excavate and excavate and excavate.

MATEUS: Because there are so many bones. We’re talking about many skeletons in the same position, in the same layer. It’s definitely a lot of fun. But scientifically, it’s much harder. If we have one single skeleton, you know exactly every bone belongs to that animal. If you have many skeletons together—is that femur, for instance, from animal to the right or the animal to the left? We don’t know.

ALEXANDRA FERNANDES (graduate student): There’s a vertebrae here.

CARL MEHLING (Senior Museum Specialist): Well, if this is the only thing in the way, maybe I can go that way, eventually.

[CHISEL CHIPPING AWAY AT ROCK]

NORELL: Collecting one bone can just take a lot of time. So you have to have large crews and you have to be able to come back to the places year after year, year after year.

MATEUS: Every time since the first day, every time we see this site, one gets overwhelmed. Overwhelmed with the landscape, with the geology of the region, but also with the amount and the quality and diversity of bones we find in the site. In the first week we got here, we found four skulls. And that’s normally, that’s more than one has in their entire life.

NORELL: Well, the thing about being a paleontologist is that you never know what you’re going to find when you go out to the desert.